tgor1-1902.] Report of the Microscopical Section, 379 
row of tentacles, presumably for the purpose of excluding 
undesirable substances. Below the tentacles is the pre- 
branchial zone, bounded on the lower or inner side by two 
bands called the peripharyngeal bands, which encircle the 
neck of the branchial sac. The upper of these bands is 
continuous in its passage round the branchial sac, but the 
continuity of the lower band is broken by its attachment to 
two other organs—one on the ventral side called the endo- 
style, and the other on the dorsal side called the dorsal lamina. 
The endostyle is a thick-walled ciliated groove running along 
the whole length of the ventral side, and terminating both 
anteriorly and posteriorly in a cul-de-sac. At the anterior 
end it isin communication with the lower of the peripharyngeal 
bands. 
The dorsal lamina is also a thick-walled ciliated groove, 
communicating at its anterior end, like the endostyle, with the 
lower of the peripharyngeal bands, and running down the 
dorsal side to the cesophagus, the entrance to which it 
encircles. 
The cesophagus forms the entrance to the stomach, an organ 
of considerable size lying across the left side of the lower part 
of the body. Its continuation is the intestinal canal, which 
starts from the ventral end of the stomach, turns back across 
the body of the animal, and after making two bends, one 
towards the anterior end of the Ascidia and the other towards 
the posterior end, it empties itself at the dorsal side into the 
atrial cavity. 
Having got thus far in the dissection of the Ascidia, we are 
able to trace the course of its nourishment. The branchial 
aperture is the mouth of the animal, and into this there flows 
a constant stream of water, carrying with it microscopic 
particles of organic matter which serve for food. The water 
passes at once into the branchial sac, then through the clefts 
or stigmata in the wall into the peribranchial cavity, whence it 
is ejected through the atrial aperture. The minute particles 
of food, on the other hand, are caught by the peripharyngeal 
bands, and carried forward along these towards the dorsal 
lamina by a flow of mucus secreted in the groove of the 
endostyle, and urged forward by the ciliary action of this 
organ, Arrived at the dorsal lamina, they descend this 
